RFR 8215643: Microbenchmarks for KeyAgreement and Cipher

[Adam Petcher]

updated webrev: http://cr.openjdk.java.net/~apetcher/8215643/webrev.01/

On 12/19/2018 4:49 PM, Jamil Nimeh wrote:

> Hi Adam.  On the whole the benchmarks look good to me.  Can I ask why 
> those ciphers and key agreement schemes that support multiple key 
> lengths aren't called out in the @Param annotations?  I'm thinking 192 
> and 256 bit for AES and maybe 1024 and 3072 and/or 4096 for DH.  Do we 
> not need numbers across various key lengths with these microbenchmarks?

There probably needs to be some balance in the default parameters that 
are included in the test. If we include too many, then the test will 
take too long to run. My strategy here is to include default parameters 
for only the most important key sizes, and for things that we want to 
keep an eye on (ECDH 521 is only there because we have been tinkering 
with it). Including AES 256 in the defaults is probably a good idea, and 
I added it in the latest webrev. I think 192 is less important, because 
it isn't widely used. For DH, benchmarking it at all may not be really 
valuable, but I added it for completeness. I don't think it is 
worthwhile to test multiple key sizes for DH, and 1024 is too small 
these days. If you have any other suggestions for default key sizes, let 
me know. But keep in mind that we don't need to be complete, because 
someone running the benchmark can always do -pkeyLength=... to choose 
other sizes.

Thanks for the review. This is my first time writing a microbenchmark, 
so I would like to also get a review from a JMH/microbenchmark expert 
before I push.